1. Field of the Invention
This invention relates to equipment for recognizing in an internal combustion engine in which an ignition voltage is supplied to each spark plug in a prescribed order by means of a distributor.
With the demand of purifying emission gas and enhancing fuel efficiency of an internal combustion engine, it has been necessary to detect firing conditions in each cylinder of the internal combustion engine so as to protect the internal combustion engine against misfire. In order to detect the firing condition in each of the cylinders, an optical sensor has been installed within the cylinders on one hand. On the other hand, a piezoelectrical sensor has been attached to a seat pad of the spark plug.
In both of the cases, however, it is troublesome and time-consuming to install the sensor to each of the cylinders, thus increasing the installation cost, and at the same time, taking much time in checking and maintenance.
Therefore, it is an object of the invention to provide an ignition detector of spark plug for use in internal combustion engines which is capable of precisely detecting a waveform of a secondary voltage applied to the spark plug installed to each cylinder of the internal combustion engine with a relatively simple structure.